It's quite simple to create an image of a disk, for example an SD card, therefore use the following command:

dd if=/path/to/device of=image.img

The /path/to/device can be found out with:

lsblk

For example it can be /dev/sda. Remind that using this method will include also empty parts. An image of a 32 GB SD card will later have a size of 32 GB although for example 16 GB are unused.

Sometimes after some weeks of uptime when I entered my office in the morning, I discovered a freezed Plasma. To fix this, enter the system via SSH and then execute this command:

sudo service sddm stop

Thereby that a system is required to save WiFi passwords in clear, it can also show those passwords to you. By running the following command, the SSID, password and a QR-code of the current connected WiFi will be displayed in your CLI:

nmcli device wifi show-password

If Discord is spamming your syslog on Ubuntu or Debian and you installed it via snap, try this:

snap connect discord:system-observe

Source: github.com/snapcrafters/discord

If you got any error of the following when running apt or anything else:

locale: Cannot set LC_ALL to default locale: No such file or directory

perl: warning: Falling back to the standard locale (“C”)

perl: warning: Setting locale failed.

Just run the following command and select the correct locale:

sudo dpkg-reconfigure locales